The present invention relates to crystals of trans-4,5-dihydroxy-2-cyclopenten-1-one of an xcex1-type having a physiological activity such as anticancer action useful in the fields of pharmaceuticals, foods and beverages.
trans-4,5-dihydroxy-2-cyclopenten-1-one has a physiological activity such as anticancer action and is a compound useful in the fields of pharmaceuticals, foods and beverages.
With regard to a method for the manufacture of trans-4,5-dihydroxy-2-cyclopenten-1-one, a chemical synthesis [Carbohydrate Research, pages 217-222 (1993) ] has been known. In addition, with regard to a practical manufacturing method, a method where uronic acid or uronic acid derivative (s) is/are heated and trans-4, 5-dihydroxy-2-cyclopenten-1-one is collected from the heated products is mentioned in WO98/13328. There is no description on crystals in trans-4,5-dihydroxy-2-cyclopenten-1-one obtained in the above-mentioned methods. With regard to a method for the manufacture of cis-4,5-dihydroxy-2-cyclopenten-1-one, there is a description in Helvetica Chimica Acta, volume 55, pages 2838-2844 (1972) and said compound was finally obtained as a sublimed substance.
Residue after concentration in vacuo and freeze-dried product of the aqueous solution of trans-4,5-dihydroxy-2-cyclopenten-1-one obtained by the above practical method are reddish brown syrupy substances usually containing 10-20% of water and they are difficult to handle and have no good thermostability.
An object of the present invention is to improve purity, thermostability and handling of trans-4,5-dihydroxy-2-cyclopenten-1-one.
The present inventors have found that stable crystals having a specific X-ray diffraction pattern can be prepared when trans-4,5-dihydroxy-2-cyclopenten-1-one (hereinafter, just referred to as xe2x80x9cthe cyclopenten onexe2x80x9d) is extracted from an aqueous solution of the cyclopenten one with an organic solvent and the extract concentrated in vacuo is crystallized, when the cyclopentenone is extracted from a residue after concentration in vacuo or a freeze-dried substance of an aqueous solution of the cyclopentenone with an organic solvent and crystallization is conducted for the extract, or when a residue after concentration in vacuo or a freeze-dried substance of an aqueous solution of the cyclopentenone is dissolved in alcohol and then an organic solvent is added to said alcoholic solution whereupon the present inventors have named said crystals as xe2x80x9cthe cyclopentenone crystals of an xcex1-typexe2x80x9d.
As compared with the conventional residue after concentration in vacuo or a freeze-dried substance of an aqueous solution of the cyclopentenone, this crystals of an xcex1-type have been found to have significantly improved purity and much improved thermostability whereupon the present invention has been accomplished.
To sum up, the present invention relates to crystals of trans-4, 5-dihydroxy-2-cyclopenten-1-one of an xcex1-type.